1. Field of the Invention
The present invention relates to a turbo-pump, and more specifically to an insulated turbine disc of the turbopump.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Turbo pumps are used in rocket engines to boost the pressure of the propellant that is being pumped in order to either cool the engine nozzle and combustion chamber and/or to introduce the propellants into the combustion chamber at high pressure. U.S. Pat. No. 5,403,165 issued to Lehe et al on Apr. 4, 1995 and entitled COMPACT HIGH POWER TURBOPUMP FOR A ROCKET ENGINE; U.S. Pat. No. 5,209,652 issued to Fischer et al on May 11, 1993 and entitled COMPACT CRYOGENIC TURBOPUMP; and U.S. Pat. No. 5,529,464n issued to Emerson et al on Jun. 25, 1996 and entitled CRYOGENIC TURBOPUMP show examples of turbopumps that pump a cryogenic fuel. Each of these three references is incorporated herein by reference. One of the major problems of turbo-pumps of the prior art is that the turbine disc is exposed to the cold temperature on one side of the rotor disc and a hot temperature of the other side. Thus, one side of the turbine disc is exposed to the propellant temperature while the opposed side is exposed to the turbine drive gas temperature. This large temperature difference—from about 330 to 1000 degrees F.—will cause the disc to warp in a parabolic shape toward the cold side of the disc. This warping can lead to shortened lifetime for parts, running clearance problems, and a host of other problems.
One prior art reference, U.S. Pat. No. 6,276,896 issued to Burge et al on Aug. 21, 2001 and entitled APPARATUS AND METHOD FOR COOLING AXI-CENTRIFUGAL IMPELLER discloses a centrifugal pump impeller with a shield plate covering a side of the impeller opposite to that of the blades. The cover plate forms a plurality of cooling air cavities in the space formed between the rotor disc and the cover plate. Cooling air is passed through the cavities in order to cool the impeller. The difference between the present invention and the Burge et al patent is that Burge patent requires cooling air while the present invention does not. The use of cooling air (or a cooling fluid) usually introduces additional losses into the system and requires additional design innovation to route the cooling gas into and out of the rotor disc.
An object of the present invention is to provide for a turbo-pump with an insulated surface such that high temperature differences across the turbine disc will not cause significant warping.
Another object of the present invention is to provide for a turbo-pump with a sealed cavity that does not require cooling fluid to reduce the heat transfer rate across the turbine disc.